Electronic systems (e.g., computers, printers, etc.) may be designed with one or more printed circuit boards that are electrically connected together to perform various functions. One of these printed circuit boards, which is commonly employed within computers, is referred to as a “motherboard”. The motherboard typically is the main printed circuit board that provides interconnections between primary electronic components of the computer such as its processor, memory and the like.
Manufacturers may follow a well-established circuit board assembly procedure in order to manufacture a fully functional circuit board. This circuit board assembly procedure may have four sequential stages of which the second, third and fourth stages are performed in an assembly line environment while the first stage is performed beforehand, normally at an off-line site, in an effort to speed up the assembly line stages. The first stage may involve programming various programmable electronic components using well-known manual or automated equipment operated by one or more persons. These programmable electronic components include, but are not limited to, read-only memory (“ROM”), erasable programmable read-only memory (“EPROM”) and electrically erasable and re-programmable non-volatile memory (typically referred to as “flash” memory). Afterwards, electronic components may be connected to the circuit board during the second or third stages.
The second and third stages may involve assembly of the circuit board by connecting surface mount technology (“SMT”) components followed by through hole mount technology (“THMT”) components through various widely known techniques. For example, the technique for connecting SMT components to the circuit board may include the following operations: (i) solder paste application, (ii) proper placement of the SMT components, and (iii) reflow soldering to establish connections between bus lines previously routed in the circuit board and the SMT components. Likewise, the technique for connecting the THMT components may include the following operations: (i) proper placement of THMT components, and (ii) wave soldering.
The final stage in manufacturing circuit boards may involve testing each component (i.e., “in-circuit” testing) as well as the entire operation of the circuit board (i.e., “functional” testing) to determine whether the circuit board is functioning properly.
In the above-described assembly process, solder may be used to connect various components to the printed circuit boards. In the past, the solder contained tin and lead with lead comprising often as much as 37% of the total solder. However, lead based solder is undesirable due to environmental concerns. As such, environmentalists and manufacturers have started to use lead-free solder to connect components to the printed circuit boards. A circuit board that does not use lead based solder may be called a lead-free circuit board. These lead-free circuit boards may need to be distinguished from printed circuit boards having lead based solder at various times over the life cycle of the printed circuit board.